1. Field of the Invention
The present invention relates to a pneumatic tire for a motorcycle.
2. Description of the Related Art
FIG. 3 is a sectional view showing a part of a conventional pneumatic tire 2 for a motorcycle. The tire 2 includes a tread 4, a wing 6, a sidewall 8, a bead 10, a carcass 12, a band 14, an inner liner 16 and a chafer 18. The tire 2 is of a tubeless type.
The sidewall 8 is extended inward in a radial direction from an end 20 of the tread 4. The sidewall 8 is constituted by a crosslinked rubber having a hardness of approximately 70.
In order to increase a rigidity of a portion of the tire 2 in which the sidewall 8 is positioned, there are investigated specifications, for example, a thickness of the sidewall 8, a position of an end 24 of a carcass ply 22 folded back through the bead 10, and a height of an apex 26 constituting the bead 10. In respect of an enhancement in a productivity and a reduction in a weight, Japanese Laid-Open Patent Publication No. 2007-118824 (US2007/95449) has disclosed an example in which there is investigated a specification of a portion in which a sidewall is positioned.
The tire 2 shown in FIG. 3 assumes such an aspect that an external surface 28 of the sidewall 8 is protruded outward in an axial direction. A thickness of the sidewall 8 portion is peculiar. When the tire 2 is flexed, a specific distortion is generated in this part. The specific distortion influences a rigidity feeling and a grip feeling in accelerating and braking operations.
When the thickness of the sidewall 8 is regulated in order to enhance the rigidity feeling and the grip feeling, a stability against a disturbance and a ride comfort are inhibited. Even if there is regulated a height HT in the radial direction from a bead base line (a solid line BBL in FIG. 3) to the end 24 of the carcass ply 22 which is folded back through the bead 10, the stability against the disturbance and the ride comfort are inhibited. Even if there is regulated a height of the apex 26 which is defined by a height HP in the radial direction from a core 30 of the bead 10 to a tip 32 of the apex 26, the stability against the disturbance and the ride comfort are inhibited.
A rigidity of the tire 2 is regulated based on a flexure confirmed by the tire 2 set into a stationary state. For this reason, it is not easy to obtain the tire 2 in which a rigidity feeling and a grip feeling in driving and braking operations are enhanced without damaging a stability against a disturbance and a ride comfort.
It is an object of the present invention to provide a pneumatic tire for a motorcycle which is excellent in the rigidity feeling and the grip feeling.